Battery indicator is inaccurate

Description

OFW: Q2C18
Build: 488

I've observed strange behavior with the battery charge indicator in the past couple builds. Sometimes, it does not decrease when unplugged or will not increase when charging. Occasionally, the charge will leap up by a large amount all at once. It generally corrects itself after a while.

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I've observed strange behavior with the battery charge indicator in the past couple builds. Sometimes, it does not decrease when unplugged or will not increase when charging. Occasionally, the charge will leap up by a large amount all at once. It generally corrects itself after a while.

I've seen cases where the EC code is failing to reset the capacity,voltage, current, etc values to zero when the battery is removed. I'm also beginning to get some reports back from the users that the battery capacity report from the EC can be erratic. The equations that govern the calculations for battery capacity on a NiMH battery are pretty complex. So I can't really say I'm that surprised.

It would be really helpful to me if you could set up some sort of userspace logging facility that can track the battery management system parameters. There is a lot of info in the battery EEPROM beyond the voltage and current.

With a newer kernel and EC code you can:

Read a unique 64-bit ID for the battery pack

Read all the values in the gas guage EEPROM using the OLPC battery driver.

With these features we can track BMS parameters on a per battery basis. This will be crucial to diagnose some of the more bizarre battery problems. One the HAL stuff settles down please contact me (richard at laptop dot org) and I'll help you get a list of EEPROM values that are important to track.

Having all that data logged across multiple charge/discharge cycles will be _really_ useful for solving the battery corner cases that I think are beginning to surface.